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Preparation method of 2-chlorophenylhydrazine sulfate

A technology of chlorophenylhydrazine and sulfate, which is applied in the field of preparation of organic compounds, can solve the problems of high impurity content, poor stability and small yield of products, and achieves the effects of improving purity, easy operation and less impurities

Inactive Publication Date: 2014-11-19
TIANJIN CHEM REAGENT RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

And the product obtained by the preparation method of existing 2-chlorophenylhydrazine sulfate has high impurity content, low purity, poor stability, and small output, which cannot meet the needs of the market

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] A preparation method for 2-chlorophenylhydrazine sulfate, comprising the following steps:

[0022] ⑴ diazotization

[0023] Add 50g of 2-chloroaniline and 150ml of 37% concentrated hydrochloric acid into a 1L three-necked flask, cool to 2°C with ice salt, add 85.7g of 35% sodium nitrite aqueous solution while stirring, and keep the temperature at 2°C for 1 hour.

[0024] ⑵ reduction

[0025] Add 450ml of 37% concentrated hydrochloric acid, 450ml of water and 120g of zinc powder in the reaction solution, keep the temperature at 18°C ​​and react until the reaction is complete, the reaction solution turns off-white, then add 20% sodium hydroxide solution until the pH value of the reaction solution is 10, After 1 hour of heat preservation at 5°C, crystals were precipitated, and 26.5 g of crude 2-chlorophenylhydrazine was obtained by filtration.

[0026] ⑶ Purification

[0027] Dissolve 26.5g of crude 2-chlorophenylhydrazine in 530g of water, heat to 60°C to dissolve it c...

Embodiment 2

[0031] A preparation method for 2-chlorophenylhydrazine sulfate, comprising the following steps:

[0032] ⑴ diazotization

[0033] Add 200g of 2-chloroaniline and 600ml of 37% concentrated hydrochloric acid into a 5L three-necked flask, cool to 2°C with ice salt, add 343g of 35% sodium nitrite aqueous solution while stirring, and keep the temperature at 2°C for 1.5 hours.

[0034] ⑵ reduction

[0035] Add 730ml of 37% concentrated hydrochloric acid, 730ml of water and 195g of zinc powder to the reaction solution, keep the temperature at 18°C ​​until the reaction is complete, the reaction solution turns off-white, then add 25% sodium hydroxide solution until the pH of the reaction solution is 10 , kept at 5°C for 1.5 hours, crystals were precipitated, and 120 g of crude 2-chlorophenylhydrazine was obtained by filtration.

[0036] ⑶ Purification

[0037] Dissolve 120g of crude 2-chlorophenylhydrazine in 2400g of water, heat it to 60°C to dissolve it completely, then add an ap...

Embodiment 3

[0041] A preparation method for 2-chlorophenylhydrazine sulfate, comprising the following steps:

[0042] ⑴ diazotization

[0043] Add 500g of 2-chloroaniline and 1500ml of 37% concentrated hydrochloric acid into a 10L three-necked flask, cool to 2°C with ice salt, add 857g of 35% sodium nitrite aqueous solution while stirring, and keep the temperature between 0 and 5°C for 1.5 hours.

[0044] ⑵ reduction

[0045] Add 730ml of 37% concentrated hydrochloric acid, 730ml of water and 480g of zinc powder to the reaction solution, keep the temperature at 18°C ​​until the reaction is complete, the reaction solution turns off-white, then add 30% sodium hydroxide solution until the pH value of the reaction solution is 10 , kept at 5°C for 2 hours, crystals were precipitated, and 290 g of crude 2-chlorophenylhydrazine was obtained by filtration.

[0046] ⑶ Purification

[0047] Dissolve 290g of crude 2-chlorophenylhydrazine in 5800g of water, heat to 60°C to dissolve it completely, ...

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Abstract

The invention relates to a preparation method of 2-chlorophenylhydrazine sulfate. The preparation method comprises the steps of diazotization, reduction, purification and salification, wherein a reaction liquid is kept strongly acidic by adopting concentrated hydrochloric acid in the diazotization and reduction steps, so that the smooth and complete proceeding of reaction is ensured; zinc powder-concentrated hydrochloric acid is adopted as a reducing agent to substitute for sodium thiosulfate, sodium hydrogen sulfite, tin protochloride-hydrochloric acid and the like in the reduction step, so that good reduction property, high yield and reaction time shortening are achieved, a product is few in impurity and high in purity because impurities, namely zinc hydroxide and the like which are generated after the reaction, are convenient to remove; and leaching is carried out by using acetone in the salification step, so that the purity of the product is enhanced, and the appearance of the product is ensured. The preparation method disclosed by the invention is stable and reliable in process and easy to operate and completely meets the requirement of market on the 2-chlorophenylhydrazine sulfate by achieving high product purity (content measured through high efficiency liquid chromatography is more than or equal to 99.1%) and yield more than or equal to 42%.

Description

technical field [0001] The invention relates to the technical field of preparation of organic compounds, in particular to a preparation method of 2-chlorophenylhydrazine sulfate. Background technique [0002] 2-Chlorophenylhydrazine sulfate, as an important intermediate in organic synthesis, is widely used in the dye and pharmaceutical manufacturing industries, and has a broad market prospect. And the prepared product of existing 2-chlorophenylhydrazine sulfate has high impurity content, low purity, poor stability and small output, which cannot meet the needs of the market. Contents of the invention [0003] The purpose of the invention is to overcome the deficiencies in the prior art and provide a preparation method of 2-chlorophenylhydrazine sulfate with high purity, large output and good stability. [0004] In order to achieve the above object, the present invention adopts the following technical solutions: [0005] A preparation method of 2-chlorophenylhydrazine sulf...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C241/02C07C243/22
Inventor 何金
Owner TIANJIN CHEM REAGENT RES INST
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